diff --git a/d09.cc b/d09.cc
index b38b724..481f042 100644
--- a/d09.cc
+++ b/d09.cc
@@ -88,8 +88,8 @@ void output_img(const vector<Pos2d> &knot, const unordered_set<Pos2d> &visited)
         TAIL,
         HEAD
     };
-    unsigned width = max_x - min_x;
-    unsigned height = max_y - min_y;
+    unsigned width = max_x + 1 - min_x;
+    unsigned height = max_y + 1 - min_y;
     auto map = vector<enum Grid>(width * height);
 
     for (auto i : visited) map[(i.y - min_y) * width + (i.x - min_x)] = VISITED;